From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752610Ab0ICGJz (ORCPT ); Fri, 3 Sep 2010 02:09:55 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:57294 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751680Ab0ICGJy (ORCPT ); Fri, 3 Sep 2010 02:09:54 -0400 Date: Fri, 3 Sep 2010 08:09:27 +0200 From: Ingo Molnar To: Eric B Munson Cc: KOSAKI Motohiro , akpm@linux-foundation.org, mingo@redhat.com, hugh.dickins@tiscali.co.uk, riel@redhat.com, peterz@infradead.org, anton@samba.org, hch@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] Add trace points to mmap, munmap, and brk Message-ID: <20100903060927.GA19074@elte.hu> References: <20100721223359.8710.A69D9226@jp.fujitsu.com> <20100727110904.GA6519@mgebm.net> <20100727201644.2F46.A69D9226@jp.fujitsu.com> <20100902134827.GA6957@mgebm.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100902134827.GA6957@mgebm.net> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Eric B Munson wrote: > Sorry for the long delay, the enter/exit routines are not compatible > with the information that these new trace points provides. When > tracing mmap, for instance, the addr and len arguments can be altered > by the function. If you use the enter/exit trace points you would not > see this as the arguments are sampled at function entrance and not > given again on exit. Also, the new trace points are only hit on > function success, the exit trace point happens any time you leave the > system call. Would it be feasible to use enter/exit information as the main source of events - and only add new tracepoints for the _missing_ information? (such as when mmap arguments change) Then user-space can combine the two. The new tracepoints would also carry useful information in themselves: they would show the cases where user-space did not get what it wished. (or so) Thanks, Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id D12FB6B0047 for ; Fri, 3 Sep 2010 02:09:41 -0400 (EDT) Date: Fri, 3 Sep 2010 08:09:27 +0200 From: Ingo Molnar Subject: Re: [PATCH 1/2] Add trace points to mmap, munmap, and brk Message-ID: <20100903060927.GA19074@elte.hu> References: <20100721223359.8710.A69D9226@jp.fujitsu.com> <20100727110904.GA6519@mgebm.net> <20100727201644.2F46.A69D9226@jp.fujitsu.com> <20100902134827.GA6957@mgebm.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100902134827.GA6957@mgebm.net> Sender: owner-linux-mm@kvack.org To: Eric B Munson Cc: KOSAKI Motohiro , akpm@linux-foundation.org, mingo@redhat.com, hugh.dickins@tiscali.co.uk, riel@redhat.com, peterz@infradead.org, anton@samba.org, hch@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: * Eric B Munson wrote: > Sorry for the long delay, the enter/exit routines are not compatible > with the information that these new trace points provides. When > tracing mmap, for instance, the addr and len arguments can be altered > by the function. If you use the enter/exit trace points you would not > see this as the arguments are sampled at function entrance and not > given again on exit. Also, the new trace points are only hit on > function success, the exit trace point happens any time you leave the > system call. Would it be feasible to use enter/exit information as the main source of events - and only add new tracepoints for the _missing_ information? (such as when mmap arguments change) Then user-space can combine the two. The new tracepoints would also carry useful information in themselves: they would show the cases where user-space did not get what it wished. (or so) Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org